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Biomedical subjects

P Oswald

Publications and source records attributed to P Oswald.

At least 19 recordsLinked to original sources
PubMed2000

On the calculation of Gibbs energy corresponding to enantioselective interactions at a direct HRGC separation of enantiomers.

A novel procedure is proposed for the calculation of Gibbs energy corresponding to enantiospecific interactions of 2-(2, 4-dinitrophenoxy)-, 2-phenoxy-, and 2-halogen-n-pentane enantiomers with a beta-cyclodextrin (ChirasilDex) stationary phase under gas chromatographic conditions. This energy is calculated from retention data as a difference between the Gibbs energy of an enantiomer and its corresponding achiral congener. The procedure for the determination of 2-(2,4-dinitrophenoxy)-, 2-phenoxy- and 2-halogen- n-pentane achiral congener retention data is discussed in detail.

Chromatography, Gas↗
PubMed1997

Liver positive enhancement after injection of superparamagnetic nanoparticles: respective role of circulating and uptaken particles.

Superparamagnetic nanoparticles have both high r1 and r2 relaxivities responsible for positive or negative enhancement properties. The aim of this study was to investigate to what extent perfusion (circulating particles) and uptake (clustered particles) mechanisms contribute to liver positive or negative enhancement using two different particles, superparamagnetic iron oxides (ferumoxides, AMI 25) and ultrasmall superparamagnetic iron oxides (ferumoxtran, AMI-227). Uptake kinetics were studied after intravenous injection of 20 micromol Fe/kg ferumoxtran on a washout liver model. Livers of 82 rats were surgically isolated and washed with saline infusion. Imaging was performed ex vivo at 0.5T with T1- and T2-weighted sequences. Enhancement kinetics of the liver were studied in vivo using MRI up to 180 min post injection of 20 micromol Fe/kg ferumoxtran (time response study) or 10, 20, 40 micromol Fe/kg ferumoxtran and 20 micromol Fe/kg ferumoxides (dose response study.) Particle uptake occurred early and resulted in a negative enhancement of the washed livers 15 min after injection of both T1 and T2 sequences. In vivo, a positive enhancement was only seen during the first five min with the lowest dose of ultrasmall superparamagnetic iron oxides and the T1 sequence. Uptake and clustering of the particles induced a negative liver enhancement. During the first minutes after injection, when uptake has not significantly occurred, perfusion imaging of the liver at a dose of 10 micromol Fe/kg results in a positive enhancement with T1-weighted sequences.

Analysis of Variance↗
PubMed1996

[Endovascular treatment of hemorrhagic renal angiomyolipoma with platinum microcoils].

Haemorrhage is the major complication of renal angiomyolipoma and is classically treated surgically, but embolization constitutes an alternative treatment. Improvement of catheters and embolization materials now allows highly selective embolization. The authors present a case in which the use of a variable stiffness catheter and platinum microcoils allowed highly selective embolization of a haemorrhagic renal angiomyolipoma while preserving the functional renal parenchyma.

Adult↗
PubMed1995

[Hepatosplenic silicosis].

A case of hepatosplenic silicosis complicating a pulmonary silicosis is reported. Numerous calcified splenic nodules seen with conventional radiology, ultrasound or computed tomography, hepatic microcalcifications and "egg shell" abdominal lymph nodes best seen with computed tomography represent the radiologic signs. However, hepatosplenic silicosis can only be confirmed by pathological examination of liver biopsies showing birefringent particles within hyalinized nodules.

Calcinosis↗
PubMed1992

[The value of computer reconstruction of the frontal and sagittal planes of the facial structures].

The authors evaluate the merits of computer reconstructions in the coronal and sagittal planes to assess the anatomy of the facial structures. If the patient can be kept motionless, the coronal plane provides information similar to those obtained by a study with direct sections. The ethmoidofrontal recesses, the lamina cribrosa, the thin relief of the middle meatus, the floor of the orbit are perfectly examined. The sagittal plane provides a new approach of the anterior and posterior cortical bone, of the frontal sinus, of the nasofrontal canal, of the ethmoidal cells, of the sphenoid sinus and of the vault of the palate.

Ethmoid Sinus↗
PubMed1990

Can chlorpromazine prevent flap necrosis?

The influence of chlorpromazine hydrochloride on failing, cranially-based dorsal flaps of female rats (Uje:WIST) was studied. The drug was injected subcutaneously into the abdomen pre- and postoperatively. The dosage was 1.5 mg/100 g preoperatively and 0.75 mg/100 g body weight every 12 hours following flap replantation for 10 consecutive days. No improvement in the survival rate was achieved by administration of chlorpromazine hydrochloride in this rat strain.

Animals↗
PubMed1988

The influence of postoperative vessel occlusion on the viability of free microvascular skin-fat flaps and island flaps in rats.

Using a method of vascular pedicle ligation without skin incision, some minor differences were found between the progress of neovascularization in microvascular free skin-fat flaps and island flaps, both with and without 1-hr ischemia in rats. Viable flap areas were established following vascular pedicle ligation (both vessels or only artery or vein), on the third day after flap replantation in both island and free flaps. Vascular pedicle occlusion on the fifth day after operation resulted in complete survival of free flaps only. Island flaps survived completely following vascular pedicle ligation on the seventh postoperative day. A clear correlation existed between the timing of vascular pedicle ligation and the necrosis and shrinkage rates. In free flaps, clinical signs of viability disturbances were seen earlier in single or total vascular pedicle occlusions, on the third or fourth day compared with island flaps. Insufficiency of the pedicle vein in island or free flaps was tolerated earlier than arterial or total pedicle occlusion. Venous occlusion three days after flap replantation caused significantly higher necrosis and shrinkage rates (p less than 0.05) in free flaps than in island flaps.

Animals↗